God made sex exclusively for marriage! Pre-marital and extra-marital sex are sins and God prohibits those who engage in them from inheriting His Kingdom.
“And they were both naked, the man and his wife, and were not ashamed.” – Genesis 2: 25
“Let thy fountain be blessed: and rejoice with the wife of thy youth. Let her be as the loving hind and pleasant roe; let her breasts satisfy thee at all times; and be thou ravished always with her love. And why wilt thou, my son, be ravished with a strange woman, and embrace the bosom of a stranger? For the ways of man are before the eyes of the LORD, and He pondereth all his goings. – Proverbs 5: 18-21
“Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind, nor thieves, nor covetous, nor revilers, nor extortioners, shall inherit the kingdom of God.” – 1 Corinthians 6: 9-11
